my 286@10 EGA https://www.flickr.com/photos/94839221@N05/al … 157660715046016

name of program?

By the look of it, I'd guess an early version of Dr. Hardware.

Yes, should be dr.hardware.

Awesome system ! Thanks for sharing; brings back many memories !

As you've already noticed, I have a board that's basically the same as yours, only yours has SIMM sockets, mine has SIPP - Advanced Computer Technology 35-7024-00-00 + Harris CS80C286-25

So, I have a few questions:
- Do you still have that board? In what configuration?
- Do you have any documentation, especially on jumper settings?
- Have you tried it with 16 MB of RAM (4 x 4 MB SIMMs)?

As of yet, all I can say is that mine is surprisingly slow, around 4700 Dhrystones (yes, at 25 MHz), while yours is 5973 (24 MHz) or 6254 (25 MHz), and Ekb's is 6374 (25 MHz).
Must be something with wait states - I'm using 70 ns modules, and I guess the board is configured accordingly.

I still have it 😉

I don't have any documentation but I did try all jumper positions and they don't do much - at least I didn't find anything different.
It is set up like on the photo - only the DIP switches matter.
I remember that SIMMs are running very hot. If I clocked the motherboard to 25Mhz it was unstable because of the memory. When I put the 12cm fan over the memory it run fine.

About 4x4MB of memory I don't recall if I tried.

kixs wrote on 2020-04-29, 13:25:

I don't have any documentation but I did try all jumper positions and they don't do much - at least I didn't find anything different.
It is set up like on the photo - only the DIP switches matter.

So I did compare the settings, and the following are different:

JP3
JP4
JP20
JP21
JP22
SW1/1
SW1/4

Most of them are located in the crystals and FPU area, with the exception of JP20 - located between the CPU and memory sockets, selects memory wait states?

I remember that SIMMs are running very hot. If I clocked the motherboard to 25Mhz it was unstable because of the memory. When I put the 12cm fan over the memory it run fine.

Strange, there are systems with 30-pin SIMMs that run with FSB faster than 25 MHz, I think up to 50 MHz.
Of course, they can't run at 0WS, but at 25 MHz it should be possible - I had a 386DX-25 machine, with DRAM set to 0WS in CMOS SETUP, and it seemed to work fine without any memory cooling.

BTW, have you experienced any problems related to the FPU?
You mentioned that CKM (pin 39) is LOW, but have you measured the CLK (pin 32) frequency?
If CLK is 50 MHz, and CKM is LOW, then 287XL runs at 25 MHz, while it's only rated for 12.5 MHz.
Hard to believe it can work overclocked by 100%, but who knows? If the 287XL is actually a "387 in 287 package", then it may be actually designed for frequencies even up to 33 MHz...

The DIP switch settings (and maybe some jumper settings) may be similar to some of the other (probably older) ACT chipset 286 boards.

There's at least one on the Stason website, the EAT-12

https://stason.org/TULARC/pc/motherboards/U/U … 286-EAT-12.html

The DIP switch block there configures installed RAM size/bank selection and 1 or 0 wait states.

The Parity select jumper is probably among the more important RAM select options not on the DIP switches.

I have an EAT-12 board that was working for a while, but after I actually set it up to boot DOS off an old hard drive and run some tests (and even played X-Wing on it for a while) it failed to POST the following day and is currently still dead. It may just be some of the DIP-20 RAM sockets went bad (they were a bit oxidized and dirty, and I swapped RAM around several times) or one or more capacitors went bad, including one ceramic cap with half the insulation broken off. (it worked in spite of that, but may have flaked out)

Didn't get a change to try overclocking it before it died. Also it uses 2-pin passive crystals rather than 4-pin active crystal oscillators.

I have another ACT based board, this one with 8 DIP-20 sockets and 4 SIPP sockets and Cotek markings on the AMI BIOS labels, so it might be a PC-Chips (or related rebrand) board. It tries to POST but hangs before the memory test starts. (the EAT-12 board came with a Quadtel BIOS, but I found the AMI one to work fine as well and was a bit more user friendly)

Both of these boards had most of the DIP and some jumper setting info printed on the PCB itself, sort of like was more common with some 486 and Socket 7 boards.

Interestingly, the same ACT chip used in these 286 boards is present as part of the ACT 386DX chipset as well.

http://www.amoretro.de/2012/08/act-386-cache- … simm-slots.html
http://www.amoretro.de/wp-content/uploads/act … ram_sockets.jpg

Same ACT27C001 chip as the 286 boards.

Couldn't find any datasheets or documentation, unfortunately.

If it has built-in LIM EMS support, the drivers for it seem to be lost as well. Though given the absence of any EMS memory configuration in the BIOS, it seems more likely to not have EMS support.

The layout of the EAT-12 is a lot like that of the PC-Chips M205 and the SIPP socketed board is a lot like the M209. Both of those use the Citygate D60 chipset (also used on some Hedaka branded boards, like the 988) which does have EMS support, but not nearly as fast 0WS performance. (it does seem to overclock well and have performance sort of half way between typical 0 and 1 ws settings on the faster chipsets; it also seems a lot less picky about RAM than 0WS on those faster boards)

The D60 chipset also supports up to 16MB of RAM and 4MB SIMM or SIPP modules (or rather, the 8MB bank size necessary for using 4MB modules). Some others that support 16MB still top out at the 2MB bank size, so you need 16 SIMM or SIPP sockets to populate 16MB. (I have a Suntac based board with 8 SIMM sockets and an 8MB limit resulting from the 2MB bank size contstraint)

I believe this ACT chipset has similar performance at 0WS to the C&T SCAT chipset and Headland HT12, but I'm not sure if it has some of the other features, like page-mode or bank-interleave. (that Suntac board with 8 SIMM slots actually supports 4-bank interleave when all the banks are populated, though that goes for 4 banks of 512kB as well)

^Hi there, good morning!

Since you mentioned the Quadtel BIOS..
I've found a Quadtel EMS driver that works with the HT12 and AMI BIOS.
https://youtu.be/DSQCKlhmEq8?t=83

Maybe there are other EMS drivers by Quadtel, too ?
If so, one of them might be suitable for your mainboard.

If memory serves me well, then I've found some EMS drivers at:

Headland HT12/A 286 chipset: UMB driver?
http://ibm-pc.org/drivers/memory/memory.htm
http://vogonsdrivers.com/index.php?catid=32

Good luck! 😀

kixs
this 286 motherboard (ACT A27C001 chipset)?
could You help me with some parts information?
- what transistors Q1 and Q2 are in there?
- capasitor C95 ?
- chip U15?
or could You attache a good quality motherboard pictures of that power side? there are the elements

thanks a lot
regards

Cezary wrote on 2020-08-04, 17:00:

kixs this 286 motherboard (ACT A27C001 chipset)? could You help me with some parts information? - what transistors Q1 and Q2 a […]
Show full quote

kixs
this 286 motherboard (ACT A27C001 chipset)?
could You help me with some parts information?
- what transistors Q1 and Q2 are in there?
- capasitor C95 ?
- chip U15?
or could You attache a good quality motherboard pictures of that power side? there are the elements

thanks a lot
regards

Didn't see your post till now. Do you still need help?

PS:
You better quote me as I get an alert. Otherwise it's a matter of luck 😉

Nice job! My actual config (LM6 37MHz, NU Si8: 18.9, Chris3D Bench: 9.0): "PC-CHIPS3" chipset (or something with this sticker on it) mobo, 25MHz Harris CPU, Cyrix 287XL+ FPU, 4MB SIMM RAM, Tseng ET4000W32i videocard, 1.2MB & 1.44MB FDD, Seagate 520MB HDD, Creative Sound Blaster Pro2.
Here is a video with some benchmarks and games:
https://www.youtube.com/watch?v=c2TBeuVWuQA